Respiratory effects of kynurenic acid microinjected into the ventromedullary surface of the rat.

نویسندگان

  • F P Tolentino-Silva
  • A K Russo
  • S L Cravo
  • O U Lopes
چکیده

Several studies demonstrate that, within the ventral medullary surface (VMS), excitatory amino acids are necessary components of the neural circuits involved in the tonic and reflex control of respiration and circulation. In the present study we investigated the cardiorespiratory effects of unilateral microinjections of the broad spectrum glutamate antagonist kynurenic acid (2 nmol/200 nl) along the VMS of urethane-anesthetized rats. Within the VMS only one region was responsive to this drug. This area includes most of the intermediate respiratory area, partially overlapping the rostral ventrolateral medulla (IA/RVL). When microinjected into the IA/RVL, kynurenic acid produced a respiratory depression, without changes in mean arterial pressure or heart rate. The respiratory depression observed was characterized by a decrease in ventilation, tidal volume and mean inspiratory flow and an increase in respiratory frequency. Therefore, the observed respiratory depression was entirely due to a reduction in the inspiratory drive. Microinjections of vehicle (200 nl of saline) into this area produced no significant changes in breathing pattern, blood pressure or heart rate. Respiratory depression in response to the blockade of glutamatergic receptors inside the rostral VMS suggests that neurons at this site have an endogenous glutamatergic input controlling the respiratory cycle duration and the inspiratory drive transmission.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Glutaminergic receptor in the rostroal ventrolateral medulla mediate the cardiovascular responses to activation of the bed nucleus of the stria terminalis in female ovariectomized rat

Introduction: Experiments were done to investigate the cardiovascular response to glutamate (Glu) injection in the bed nucleus of stria terminalis (BST) in urethane anesthetized ovariectomized (OVX) or OVX estrogen  treated (OVX+E)  female Wistar rats. In this study also the effect of glutaminergic system of the rostral ventrolateral medulla (RVLM) on Glu stimulation of cardiovascular...

متن کامل

Analgesic effect of morphine microinjected into the nucleus raphe magnus after electrolytic lesion of nucleus cuneiformis in tail-flick and formalin tests in rat

Introduction: The antinociceptive effect of morphine is, in part, mediated through the activation of a descending pathway. One of the major components of this pathway is the nucleus raphe magnus (NRM). Our previous study demonstrated the involvement of NRM in the analgesic effect of morphine microinjected into the nucleus cuneiformis (NCF) in a descending manner. The aim of the current study...

متن کامل

Ellagic acid attenuates enhanced acetylcholinesterase reactivity in an experimental model of Alzheimer′s disease induced by beta amyloid25-35 in the rat

Background and Objective: Alzheimer’s disease (AD) is a multifactorial disease with debilitating consequences and few therapeutic strategies exist for it. With regard to antioxidant capacity and anti-β-amyloid polymerization potential of ellagic acid, this study was conducted to evaluate the effect of this substance on enhanced acetylcholinesterase reactivity in an experimental model of Alzheim...

متن کامل

Blockade of Opioid Receptors Located in the Rat Nucleus Cuneiformis Reduced the Antinociceptive Responses of Local But not Systemic Administration of Morphine in Formalin Test

ABSTRACTPrevious studies have shown the role of opioid receptors located in the nucleus cuneiformis (CnF) in acute pain, but not in chronic pain models. In the present study, we have determined that possible effects of these receptors at the CnF on both early and late phases of formalin test following local and systemic morphine administration. Each rat was given a subcutaneous 50-μl injection ...

متن کامل

Effects of Acute Intraperitoneal Injection on Plural Rat Lungs

Purpose: Sulfur mustard (SM), a highly toxic chemical warfare, primarily targets the skin, eye and respiratory tract. Respiratory tract lesions are the most disabling consequences. Mast cells, containing special granules that store histamine and heparin, release leukotrienes. It is known that the surface of mast cells contains specific receptors for 19B. Therefore, mast cells promote allergic r...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:
  • Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas

دوره 31 10  شماره 

صفحات  -

تاریخ انتشار 1998